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Steady‐state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide
Ventilatory acclimatization (VA) is important to maintain adequate oxygenation with ascent to high altitude (HA). Transient hypoxic ventilatory response tests lack feasibility and fail to capture the integrated steady‐state responses to chronic hypoxic exposure in HA fieldwork. We recently character...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
John Wiley and Sons Inc.
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9718940/ https://www.ncbi.nlm.nih.gov/pubmed/36461658 http://dx.doi.org/10.14814/phy2.15521 |
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author | Cates, Valerie C. Bruce, Christina D. Marullo, Anthony L. Isakovich, Rodion Saran, Gurkarn Leacy, Jack K. O′Halloran, Ken D. Brutsaert, Thomas D. Sherpa, Mingma T. Day, Trevor A. |
author_facet | Cates, Valerie C. Bruce, Christina D. Marullo, Anthony L. Isakovich, Rodion Saran, Gurkarn Leacy, Jack K. O′Halloran, Ken D. Brutsaert, Thomas D. Sherpa, Mingma T. Day, Trevor A. |
author_sort | Cates, Valerie C. |
collection | PubMed |
description | Ventilatory acclimatization (VA) is important to maintain adequate oxygenation with ascent to high altitude (HA). Transient hypoxic ventilatory response tests lack feasibility and fail to capture the integrated steady‐state responses to chronic hypoxic exposure in HA fieldwork. We recently characterized a novel index of steady‐state respiratory chemoreflex drive (SSCD), accounting for integrated contributions from central and peripheral respiratory chemoreceptors during steady‐state breathing at prevailing chemostimuli. Acetazolamide is often utilized during ascent for prevention or treatment of altitude‐related illnesses, eliciting metabolic acidosis and stimulating respiratory chemoreceptors. To determine if SSCD reflects VA during ascent to HA, we characterized SSCD in 25 lowlanders during incremental ascent to 4240 m over 7 days. We subsequently compared two separate subgroups: no acetazolamide (NAz; n = 14) and those taking an oral prophylactic dose of acetazolamide (Az; 125 mg BID; n = 11). At 1130/1400 m (day zero) and 4240 m (day seven), steady‐state measurements of resting ventilation (V̇(I); L/min), pressure of end‐tidal (P(ET))CO(2) (Torr), and peripheral oxygen saturation (SpO(2); %) were measured. A stimulus index (SI; P(ET)CO(2)/SpO(2)) was calculated, and SSCD was calculated by indexing V̇(I) against SI. We found that (a) both V̇(I) and SSCD increased with ascent to 4240 m (day seven; V̇(I): +39%, p < 0.0001, Hedges' g = 1.52; SSCD: +56.%, p < 0.0001, Hedges' g = 1.65), (b) and these responses were larger in the Az versus NAz subgroup (V̇(I): p = 0.02, Hedges' g = 1.04; SSCD: p = 0.02, Hedges' g = 1.05). The SSCD metric may have utility in assessing VA during prolonged stays at altitude, providing a feasible alternative to transient chemoreflex tests. |
format | Online Article Text |
id | pubmed-9718940 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | John Wiley and Sons Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-97189402022-12-06 Steady‐state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide Cates, Valerie C. Bruce, Christina D. Marullo, Anthony L. Isakovich, Rodion Saran, Gurkarn Leacy, Jack K. O′Halloran, Ken D. Brutsaert, Thomas D. Sherpa, Mingma T. Day, Trevor A. Physiol Rep Original Articles Ventilatory acclimatization (VA) is important to maintain adequate oxygenation with ascent to high altitude (HA). Transient hypoxic ventilatory response tests lack feasibility and fail to capture the integrated steady‐state responses to chronic hypoxic exposure in HA fieldwork. We recently characterized a novel index of steady‐state respiratory chemoreflex drive (SSCD), accounting for integrated contributions from central and peripheral respiratory chemoreceptors during steady‐state breathing at prevailing chemostimuli. Acetazolamide is often utilized during ascent for prevention or treatment of altitude‐related illnesses, eliciting metabolic acidosis and stimulating respiratory chemoreceptors. To determine if SSCD reflects VA during ascent to HA, we characterized SSCD in 25 lowlanders during incremental ascent to 4240 m over 7 days. We subsequently compared two separate subgroups: no acetazolamide (NAz; n = 14) and those taking an oral prophylactic dose of acetazolamide (Az; 125 mg BID; n = 11). At 1130/1400 m (day zero) and 4240 m (day seven), steady‐state measurements of resting ventilation (V̇(I); L/min), pressure of end‐tidal (P(ET))CO(2) (Torr), and peripheral oxygen saturation (SpO(2); %) were measured. A stimulus index (SI; P(ET)CO(2)/SpO(2)) was calculated, and SSCD was calculated by indexing V̇(I) against SI. We found that (a) both V̇(I) and SSCD increased with ascent to 4240 m (day seven; V̇(I): +39%, p < 0.0001, Hedges' g = 1.52; SSCD: +56.%, p < 0.0001, Hedges' g = 1.65), (b) and these responses were larger in the Az versus NAz subgroup (V̇(I): p = 0.02, Hedges' g = 1.04; SSCD: p = 0.02, Hedges' g = 1.05). The SSCD metric may have utility in assessing VA during prolonged stays at altitude, providing a feasible alternative to transient chemoreflex tests. John Wiley and Sons Inc. 2022-12-02 /pmc/articles/PMC9718940/ /pubmed/36461658 http://dx.doi.org/10.14814/phy2.15521 Text en © 2022 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society. https://creativecommons.org/licenses/by/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Original Articles Cates, Valerie C. Bruce, Christina D. Marullo, Anthony L. Isakovich, Rodion Saran, Gurkarn Leacy, Jack K. O′Halloran, Ken D. Brutsaert, Thomas D. Sherpa, Mingma T. Day, Trevor A. Steady‐state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide |
title | Steady‐state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide |
title_full | Steady‐state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide |
title_fullStr | Steady‐state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide |
title_full_unstemmed | Steady‐state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide |
title_short | Steady‐state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide |
title_sort | steady‐state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: effect of acetazolamide |
topic | Original Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9718940/ https://www.ncbi.nlm.nih.gov/pubmed/36461658 http://dx.doi.org/10.14814/phy2.15521 |
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